Scant savings you say...
and your considering a Clifton?
Cheapest surface plate you can find more than likely is a piece of float glass
not plate glass, nor toughened.
Float glass will have a green tinge to it. get the thickest piece you can find.
try a fridge shelf and some ink to simulate Prussian blue .
Or try and find an offcut or broken piece of stone or black granite stove hearth from a stove
or ceramic shop who do fireplaces.
You will have to find a piece of dead flat something to check this, and have a flat surface to lay the glass on so it won't deflect, if you cant find granite/stone .
Rub the flat thing on the surface plate and look for where the ink rubs off, orientate the flat thing
the other way around and repeat, you should get the same result.
You will be very hard pressed to find a good tutorial about lapping planes on youtube
You can't just rub a plane on a dead flat surface plate with spotlessly clean paper and get a true
flat surface on your plane sole, as you need to have the edges perimeter of the plane proud
, otherwise you will create a rocking effect, both lengthwise and widthwise.
The most famous lifestyle woodworker has a video which you should avoid, avoid like the plague!
You need abrasive bonded to the surface plate, spray adhesive will do, lesser than the width and length of the plane, this will hold another sheet the same width secure.
and don't touch the edges of your plane with it!
The edges needs to be proud so that 5 passes will finish it off, no more!
If I were near broke I would look for the same plane as linked but waiting for auctions instead
and get one with a bit of blemishing all over for about 27 quid for a no.5 1/2 Stanley.
you should be able to get a jack, joiner and smoother for the price of what you mentioned first.
You want to see the plane not touching in the middle, propellor-ing
The plane needs to be under tension with the lever cap and blade retracted.
If you do this correctly you will see the plane pivot from the toe and the heel, as in
lightly holding the casting at the very edge with very light fingers.
pivot from the opposite end and the result should be the same.
Prussian blue is the key word you should look for, an precision engineering term, these are the guys
you should look at, as no woodworking videos display these skills on video.
No matter how convincing they sound, if they are abrading the edges of the plane, they don't know what their talking about!
Dont be fooled by high quality video production!
The plane needs a minute hollow so only the very last five passes will make the edges come down
to the same level as the middle of the sole.
Have to go now, cant be more specific
Tom